Share-based compensation - Options (Details) - $ / shares |
12 Months Ended | |
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Dec. 31, 2019 |
Dec. 31, 2018 |
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| Options granted on market value at grant date | ||
| Number of options granted (in shares) | 15,679,383 | 20,771,970 |
| Weighted average fair value (in dollars per share) | $ 0.48 | $ 0.87 |
| Options with nominal exercise price | ||
| Number of options granted (in shares) | 8,020,410 | |
| Number of RSU-style options granted | 8,020,410 | 8,603,676 |
| Weighted average fair value of RSU-style options granted | $ 0.86 | $ 1.37 |
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the nominal exercise price. No definition available.
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- Definition Gross number of share options (or share units) granted with nominal exercise price during the period. No definition available.
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- Definition Gross number of share options (or share units) granted during the period. No definition available.
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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